Sceptile has two Swords Dance sets with similar movesets, one intended for Unburden sweeps late-game, and the other a typical LO Swords Dance Sceptile that can sweep in a wider range of situations and needs less support. They're just different enough to warrant different sets because of the playstyle, according to Oglemi (I know this because I proposed the LO SD set in the RU Analysis Discussion Thread).

Alakazam is a different story. The Focus Sash set plays nothing like the Sub + 3 Attacks or Calm Mind sets on site, and it does not fit into either because it lack the move that gives either set its name (Substitute and Calm Mind), instead carrying a Hidden Power of choice. The Sub + 3 Attacks set is intended to set up a sub on the switch and then wreak havoc, while the Calm Mind set is more of a sweeper. Neither of them is intended as a dedicated Revenge Killer, which the Focus Sash set most definitely is. PK Gaming gave it an approval, while Delta 2777 and Iconic discussed it and decided that it was too similar to the current sets on-site and that the on-site set simply required a bigger AC paragraph.

What is the general concensus on this? Do we or do we not use playstyle as a determining factor in what sets go into analyses?

You missed the part where the two SD sets in question differ by 2 moves, the item, the choice of nature, and the EV spread. Generally it's "amount of moves and ev spread that differ" before there's a difference in sets.

In the end it'll always be subjective, but the Sceptile example isn't very good. It's not playstyle, it's similarity of movesets. You can't just say "they both sweep with SD, they must be the same set". However, you have to consider that the differences between the sets are minute on a Pokemon like Alakazam, and significant in the case of the two Sceptile sets in question.

True. I should probably have picked a better example, because I'm sure they're out there. The Alakazam thread is enough by itself, though, for the purposes of this discussion, since it contains both a QC Approval and a QC Rejection.